In recent years, as technology of storage battery progresses, such as a lithium ion secondary battery, use of storage batteries to a large-scale power-storage system is considered. Taking lithium ion secondary batteries as an example, the power storage capacity of a single cell is on the order of approximately 100 watt hours (Wh). Therefore, to implement a storage battery device of the order of megawatt hour, it is necessary to arrange cells of the order of several thousands to tens of thousands in serial or parallel, and to configure the storage device that has a desired voltage and current capacity.
In such a case, a technique of making a number of sets of battery modules that are constituted in a unit of several tens of voltages (V) and several tens of amperes (A), and of monitoring a state of all battery modules by centralized control with a battery management unit (BMU) has been generally adopted.
In communication between the BMU and a battery module, for example, communication (transmission and reception) in accordance with the controller area network (CAN) standards is performed. In a large-capacity storage-battery system, the number of battery modules is large, and therefore, a communication line, namely, a transmission distance, becomes long.
For this reason, while a battery control system can be configured at a lower voltage because it can be operated by low power, a communication system is required to be operated by high power, thereby requiring a higher voltage. Accordingly, two power supply systems are necessary.
In the large-capacity storage-battery system configured as above, when a power supply voltage temporarily becomes low, there can be a case that the communication system is in an inoperable state while the battery control system is operable depending on the voltage.
In such a case, to secure reliability, resetting and rebooting the battery control system and the communication system of the storage battery system when the power supply voltage recovers has conventionally been practiced.
Accordingly, a malfunction that the storage battery system temporarily stops can occur.
The present invention has been achieved in view of the above problem, and provides a cell monitoring device, a method, and a computer program product that enable to recover a communication system certainly, avoiding a stop of an entire storage battery system.